I have a customer that is getting the message to empty the finisher tray after completing a stapled job. This happens only every couple of weeks, and is quickly solved by reaching inside and touching the alignment tray paper sensor. There is never anything on the sensor, and swiping my finger over it always clears it up - but rebooting the machine doesn't. I've tried replacing the sensor, but it keeps coming back. Since rebooting the machine doesn't reset it, I can't imagine that it's the finisher PWB. Any ideas?